1. Field of the Invention
The present invention relates to a cooling system and a method for controlling the cooling system which cool an object to be cooled by circulating a refrigerant.
2. Description of Related Art
Conventionally, there is adopted a cooling system which is directed to improvement on heat conveyance efficiency by latent heat transfer and cooling an object to be cooled without circulating chilled water. In the cooling system, a condenser at the first side performs heat-exchange between a chilled water and a refrigerant to condense the refrigerant, and the condensed refrigerant is supplied to the evaporator at the second side to perform heat-exchange with the object to be cooled (air etc.).
Such a cooling system cools the object to be cooled by use of evaporation heat of the refrigerant to be gasified (evaporated) by the evaporator. Therefore, the cooling system requires regulating the flow-rate of the refrigerant to flow in the evaporator and keeping an evaporation pressure in the evaporator under a predetermined value.
As such a technique of the cooling system, for example, the technique described in the Patent Document 1 (Patent National Publication of translated version NO. 2007-5141212) is disclosed. The technique disclosed in the Patent Document 1 includes, in a vicinity of the evaporator, a flow-rate regulating valve for regulating a flow rate of the refrigerant. This technique regulates the flow rate of the refrigerant in response to variation of the load, appropriately keeping the flow rate of the refrigerant to flow into the evaporator.
However, in the technique disclosed in the Patent Document 1, when the circulation flow rate of the refrigerant is decreased during partial load operation, the refrigerant pressure in the system is lowered to lower the evaporation temperature of the refrigerant in the evaporator, occasionally excessively cooling an object for being cooled (air).
The invention is directed to a cooling system and a method for controlling the cooling system, which appropriately cool an object to be cooled even under a partial load operation.